The present invention relates to gas generating systems used, for example, to inflate air bags in a vehicle occupant protection system and, more particularly, to an improved gas generating system that features a more efficient method of assembly.
Gas generating systems for deploying an air bag in a motor vehicle generally employ a gas generator in fluid communication with an uninflated air bag. A firing circuit typically triggers the gas generating system when the sensed vehicle acceleration exceeds a predetermined threshold value, as through the use of an acceleration-responsive inertial switch. In many designs, the gas generating system is assembled by welding the housing to other components integrated therein.
The gas generator housing must be pierced or perforated with gas exit orifices to permit egress of gases produced upon gas generator activation. Formation in metal housing components of small diameter holes (i.e., holes having a diameter less than twice the thickness of the metal from which the component is formed) result in high punch wear and increased breakage of punches, resulting in higher tooling costs. Also, when welding, precautions must be taken to ensure that the gas generator housing is not excessively heated to prevent auto ignition of the gas generant contained within. Furthermore, the cost and complexity of welded designs is necessarily increased. In addition, in gas generator housings formed from housing portions secured together in a nested relationship, gas exit orifices formed in one of the housing portions must often be aligned with gas exit orifices formed in the other housing portion in order for the gas to properly exit the housing. This need for alignment between the two sets of gas exit orifices can increase the time and fixture costs required for gas generator assembly. In view of the above, a gas generator design not requiring a welded or pierced assembly would therefore be an improvement in the art.